This invention relates to a process for stabilizing (thermosetting) a pitch fiber in preparation for carbonization to carbon fiber.
Pitch fiber is normally melt-spun from mesophase or isotropic pitch or combinations thereof. The melt-spun fiber is then stabilized, also referred to as thermoset, in the presence of an oxidizing gas such as air, oxygen or ozone. It is believed that a certain degree of cross-linking occurs during stabilization which allows the fiber to be subsequently exposed to much higher temperatures without deformation or fusion. Following stabilization, the fiber is generally subjected to elevated temperatures in an inert atmosphere to carbonize the fiber.
The time needed for oxidative stabilization is relatively long. The present invention concerns an improvement in this step which accelerates stabilization.